The collection, processing, and distribution facilities for many products, such as oil and gas, are typically spread over a wide geographical area with numerous remote locations. There is a need to regularly monitor and control these facilities for such purposes as product flow control, fault detection, and consumption measurement. One or more centralized stations are desirable to monitor and control the facilities, since many activities involved in the product collection, processing, and distribution process require coordination and cooperation between two or more facilities. This drives a need for the central station to receive data from a plurality of facilities for monitoring purposes and to transmit control commands, such as to open or close flow control valves. Remote monitoring and control (“RMC”) systems are widely used in various areas such as security, energy market de-regulation, and traffic control.
Remote monitoring and control continues to grow in terms of capability and number of deployments. In addition, advancements in computer software and electronic technologies are making it increasingly feasible to implement remote monitoring and control in new applications.
Of particular interest are legacy RMC systems. The term “legacy” as used herein is intended to describe, without limitation, any existing installed RMC system or any contemporary version, configuration, combination or assembly of remote monitoring host application computer programs and remote devices that do not directly utilize packet-switching data or Internet Protocol networks. In most legacy RMC systems, communication sessions between a host computer or “master” at a central station, and a remote device or “slave” at a remote station are originated by the host computer. One skilled in the art will note that an analogy to modem client-server structured networks exists wherein the host computer is a client and the remote device is a server. A serious drawback to this approach becomes evident when the communication sessions are configured to take place using publicly accessible wired or wireless Internet Protocol (“IP”) networks. This is because a potential security risk exists wherein remote monitoring and control signals may be routed through a number of servers, exposing the signals to interception and tampering.
Many RMC communications are serial and half-duplex in nature, wherein commands are issued by the master and responses are returned by the slave. Although some communication standards exist, the command-response structure or protocol, as well as the remote device data structure or “payload” delivered by the protocol, is typically non-standard and often proprietary to the vendor of the RMC system. This tends to create barriers to market entry by any party that would seek to augment or modify such proprietary systems.
Another drawback of legacy RMC systems is the wide area network (“WAN”) typically used to connect the remote device and the host computer. A physical real-time switched circuit is typically dedicated to a data communication link that has been established between the host and the remote device. Although the physical circuit may be either wired or wireless, the dedicated nature of the circuit requires that remote monitoring system owners and/or operators pay for the circuit even when it is not in use. System expenses associated with dedicated communication links include physical facilities, maintenance and, in the case of wireless links, license fees.
The technological evolution of modem telephony is quickly replacing circuit-switched service with packet-switched or “store-and-forward” service, as exemplified by Internet Protocol. With packet-switching technology, physical circuits are shared by a plurality of users in time and/or frequency domains. These physical circuits may be based on either wired or wireless technology, but regardless of the physical nature of the circuit, a virtual circuit appears to be dedicated to each user desiring to send a packet of information. Packets, in turn, transport the protocol commands and responses that implement the remote monitoring and control application, as described above.
Because of the efficiency of packet switching, wireless IP network operators, whether private or public, offer their constituents significant price and performance advantages over the legacy dedicated switched-circuit environment. Among these advantages, higher data throughput and reduced pricing for a given amount of data transmitted are perhaps the most attractive to users. Consequently, remote monitoring system operators are motivated to move their applications to wireless IP networks. Unfortunately, the potential gains from migrating to wireless IP are often offset by the expense and technical difficulties associated with the migration. This is because the technical and operational interface to wireless IP networks is typically not compatible with legacy remote monitoring host application computer programs and remote devices. Typical consequences of the incompatibility are lost data packets and transmission latency introduced by the store-and-forward nature of packet switching. In addition, the protocols used by real-time circuit-switched facilities can cease to function when subjected to packet transmission errors and/or delay. This further drives a need to modify legacy remote monitoring systems for compatibility with packet-switched networks. This can be an expensive undertaking, making such conversions economically unfeasible.
What is needed is a cost-efficient and operationally transparent interface method and apparatus that will support data transport on wireless IP networks while offering a conversion process that eliminates the need to modify legacy remote monitoring host application computer programs or remote devices while at the same time providing a single server system which is practical to secure from intruders.